Use of compound-specific stable carbon isotope analyses to demonstrate anaerobic biodegradation of MTBE in groundwater at a gasoline release site

Currently it is unclear if natural attenuation is an appropriate remedial approach for groundwater impacted by methyl tertiary butyl ether (MTBE). Site-characterization data at most gasoline release sites are adequate to evaluate attenuation in MTBE concentrations over time or distance. But, demonstrating natural biodegradation of MTBE requires laboratory microcosm studies, which could be expensive and time-consuming. Recently, compound-specific carbon isotope ratio analyses (13C/12C expressed in delta13C notation) have been used to demonstrate aerobic biodegradation of MTBE in laboratory incubations. This study explored the potential of this approach to distinguish MTBE biodegradation from other abiotic processes in an anaerobic groundwater plume that showed extensive decrease in MTBE concentrations. To our knowledge, this is the first study to use delta13C of MTBE data in groundwater and laboratory microcosms to demonstrate anaerobic biodegradation of MTBE. The delta13C of MTBE in monitoring wells increased by up to 31 per thousand (-25.5 per thousand to +5.5 per thousand) along with a 40-fold decrease in MTBE concentrations. Anaerobic incubations in laboratory microcosms indicated up to 20-fold reduction in MTBE concentrations with a corresponding increase in delta13C of MTBE of up to 33.4 per thousand (-28.7 per thousand to +4.7 per thousand) in live microcosms. Little enrichment was observed in autoclaved controls. These results demonstrate that anaerobic biodegradation was the dominant natural attenuation mechanism for MTBE at this site. The estimated isotopic enrichment factors (epsilon(field) = -8.10 per thousand and epsilon(lab) = -9.16 per thousand) were considerably larger than the range (-1.4 per thousand to -2.4 per thousand) previously reported for aerobic biodegradation of MTBE in laboratory incubations. These observations strongly suggest that delta13C of MTBE could be potentially useful as an "indicator" of in-situ MTBE biodegradation.     

An evaluation of compound-specific isotope analyses for assessing the biodegradation of MTBE at Port Hueneme, CA

The use of compound-specific isotope analysis (CSIA) as a diagnostic tool for MTBE biodegradation in aquifers was tested at the Port Hueneme, CA site. There, a 1500-m long dissolved MTBE plume and associated engineered aerobic flow-through biobarrier have been well-studied, leading to delineation of regions of known significant and limited bioattenuation. This allowed comparison of field-scale CSIA results with a priori knowledge of aerobic MTBE biodegradation, leading to conclusions concerning the utility of CSIA as a diagnostic tool for other aerobic biodegradation sites. Groundwater samples were collected and analyzed for both 13C and 2H (D) in MTBE through the bioactive treatment zone and within the larger MTBE plume. For reference, the 13C enrichment factor for MTBE biodegradation in laboratory-scale microcosms using site groundwater and sediments was also quantified. Aerobic microcosms showed a 13C enrichment of 5.5 to 6.4 +/- 0.2 per thousand over a two-order of magnitude concentration decrease, with an average isotope enrichment factor (epsilon(c)) of -1.4 per thousand, in agreement with other aerobic microcosm studies. Less 13C enrichment (about 25%) was observed for similar MTBE concentration reductions in groundwater samples collected within the aerobic biotreatment zone, and this enrichment was comparable to the scatter in delta13C values within the source zone. Increasing enrichment with decreasing MTBE concentration seen in microcosm data was not evident in either the 13C or D field data. The discrepancy between field and laboratory data may reflect small-scale (<1 m) spatial heterogeneity in MTBE biodegradation activity and the mixing of water from adjacent strata during groundwater sampling; for example, relatively nonattenuated MTBE-impacted water from one stratum could be mixed with highly attenuated/low-MTBE concentration from another, and this could produce a sample with both reduced MTBE concentration and low enrichment. Overall, the results suggest that 13C data alone may produce inconclusive results at sites where MTBE undergoes aerobic biodegradation, and that even with two-dimensional CSIA (13C and D), an increase in the confidence of data interpretation may only be possible with data sets larger than those typically collected in practice.     

二维码技术的应用现状及用于食品添加剂 系统管理的可行性

二维码识别技术是一种具有汉字编码特性, 可以储存大量产品信息, 使用方式简单便捷的数据携带、传递的高科技手段。基于该技术, 本文探讨了食品添加剂可追溯系统的补充方案。该方案不仅可以为消费者提供详细的食品添加剂信息, 而且为生产企业和监管部门提供了良好的管理和监督平台。     

Genetic evaluation of mastitis resistance using a first-passage time model for wiener processes for analysis of time to first treatment

A Wiener process is a Brownian-motion process initiated in a certain state in a state space, and the first passage time is defined as the time of the process to reach a predefined absorbing state where the process stops. Time from 31 d prepartum to first treatment of clinical mastitis (CM) was modeled as first passage times of such Wiener processes. Two processes were used to allow for several risk factors, and for each process, initiation was at some arbitrary time point, in a certain health state with drift toward or away from absorption (disease). The drift parameter of each process was expressed as linear functions of covariates (year of calving and sire). First passage time was defined as the time from process initiation until the first health status process reached zero (absorption). The model was fitted to records for 36,178 first-lactation daughters of 245 Norwegian cattle sires using a Bayesian approach and Markov chain Monte Carlo methods. Genetic evaluation of sires was carried out by calculating the posterior probability of no CM (the value of the survival function) by d 331, i.e., 300 d after first calving. Alternatively, sire evaluation was based on the integrated area under the survival curve. These measures were highly correlated (0.999), which indicates a small degree of crossings of the sire-dependent survival curves. Hence, sire-specific hazards were close to proportional, resulting in a higher rank-correlation to sire evaluations from a survival model with proportional hazards than to the results from a multivariate threshold model.     

Adjoint sensitivity analysis for a three-dimensional photochemical model: application to Southern California

An adjoint method was used to investigate the sensitivity of peak ozone at selected sites in Southern California to nearly 900 model inputs including surface emissions, reaction rate coefficients, dry deposition velocities, boundary conditions, and initial conditions. Simulations showed large changes in ozone and ozone sensitivities at three sites investigated between summers 1987 and 1997 due to emission reductions. However, only small changes in ozone and ozone sensitivities were predicted between 1997 and 2010. Sensitivities of the differences in ozone between simulations with different emission scenarios were calculated and compared to sensitivities of ozone in each simulation. In some cases, the sensitivities of ozone differences were smaller than those of ozone itself, but in other cases, such as when the sensitivityto NOx emissions changed sign, sensitivities of differences were larger. The adjoint method was most useful for determining when and where model inputs affect, or have the potential to affect, an ozone response. For example, the method was used to plot the spatial distribution of important emission source regions to 1-hour versus 8-hour peak ozone. Changes in the distribution and sign of the adjoint function for emitted species revealed changes in the area of influence of pollutant emissions on peak ozone due to emission controls. The adjoint method provides useful information complementary to that obtained from forward sensitivity analysis methods.     

Site-dependent life-cycle analysis by the SAME approach: its concept usefulness, and application to the calculation of embodied impact intensity by means of an input-output analysis

This paper describes a practical approach to site-dependent life-cycle analysis (SDLCA) that differentiates site-dependent environmental impacts from a system's processes by considering the geographical conditions of each process. This approach converts an environmental output into its impacts by using site-dependent characterization factors (SDCFs). This approach defines an area-the Spatial Area of iMpact Equivalency (SAME)-within the boundaries of the geographical system during site-dependent life-cycle inventory (SDLCI) analysis and calculates an environmental output from a process for the SAMEs. Each SAME represents a collection of geographical areas with internally homogeneous environmental impacts and can be mapped using a geographic information system. Preparing a SDLCI and SDCFs based on SAMEs facilitates the implementation of SDLCA by permitting the use of fewer regions during SDLCI. To demonstrate application of the SAME approach, an embodied impact intensity was formulated; it quantifies the impact directly and indirectly on the basis of the unit activity of a sector by means of input-output analysis with SDCFs. The validity of using SAMEs for SDLCA is demonstrated through two case studies: one studying suspended particulate matter, and one studying benzene. In both cases, the impact intensities are calculated using the SAME approach and the results are compared with those of site-generic LCI.     

New tools for phenotypic analysis in Candida albicans: the WAR1 gene confers resistance to sorbate

Availability of the complete sequence of the Candida albicans genome allows for global gene analysis. We designed a gene deletion method to facilitate such studies. First, we constructed C. albicans strains that are both Deltaura3 and Deltatrp1. Second, we designed a system that relies on in vitro recombination, using the Gateway((R)) technology, for efficient generation of deletion cassettes. They are generated in two steps: (a) upstream and downstream DNA fragments of the chromosomal region to be deleted are amplified by PCR and introduced into two separate entry vectors; (b) the second step involves a quadruple recombination event including the two entry vectors, a plasmid bearing a marker of interest and a destination vector, in order to generate a plasmid containing the deletion cassette. The deletion plasmid contains very rare restriction sites for convenient excision of the knockout cassette. Selection in C. albicans can be performed with one of the following markers: the C. albicans URA3 gene, a modified S. cerevisiae TRP1 gene or the mycophenolic acid resistance (MPA(R)) gene. Upon integration into the genome, these markers can be removed by the use of 5-fluoroorotic acid (URA3), 5-fluoroanthranilic acid (TRP1) or the FLP recombinase (MPA(R)). Using this approach, we show that removal of the C. albicans orf19.1035 gene results in sensitivity to the weak acid sorbate, while its overexpression increases resistance to this compound. We named it WAR1, in analogy to its S. cerevisiae orthologue.     

New approach for aerosol profiling with a lidar onboard an ultralight aircraft: application to the African Monsoon Multidisciplinary Analysis

A new airborne instrumental payload has been designed for an ultralight aircraft to determine the vertical profile of aerosol optical properties. It is based on Lidar Aérosols UltraViolet Aéroporté (LAUVA), a compact backscattering lidar system emitting at the wavelength of 355 nm. We operated this airborne configuration in the Sahel from the city of Niamey (Niger) during the first campaign of the African Monsoon Multidisciplinary Analysis (AMMA) in January-February 2006, when aerosols from both soil dust and savannah fires cause large visibility reductions. We take advantage of the lidar capability of pointing in different directions for retrieving the vertical profile of the aerosol backscatter to extinction ratio (BER). A synergy with a scatterometer (880 nm) and a ground-based sunphotometer allows us to further determine the vertical profile of Angstr?m exponent (a). We identify three types of aerosol layers up to about 5 km below the free troposphere, dominated by biomass burning (BB) particles, mineral dust (D) particles, and a mixing between BB and D particles, respectively, associated with BER (a) values close to 0.008 sr(-1) (1.5), 0.025 sr(-1) (0), and 0.015 sr(-1) (0.4-1).     

Use of global sensitivity analysis in quantitative microbial risk assessment: application to the evaluation of a biological time temperature integrator as a quality and safety indicator for cold smoked salmon

The aim of this study was to apply a global sensitivity analysis (SA) method in model simplification and to evaluate (eO)^®, a biological Time Temperature Integrator (TTI) as a quality and safety indicator for cold smoked salmon (CSS). Models were thus developed to predict the evolutions of Listeria monocytogenes and the indigenous food flora in CSS and to predict TTIs endpoint. A global SA was then applied on the three models to identify the less important factors and simplify the models accordingly. Results showed that the subset of the most important factors of the three models was mainly composed of the durations and temperatures of two chill chain links, out of the control of the manufacturers: the domestic refrigerator and the retail/cabinet links. Then, the simplified versions of the three models were run with 10⁴ time temperature profiles representing the variability associated to the microbial behavior, to the TTIs evolution and to the French chill chain characteristics. The results were used to assess the distributions of the microbial contaminations obtained at the TTI endpoint and at the end of the simulated profiles and proved that, in the case of poor storage conditions, the TTI use could reduce the number of unacceptable foods by 50%.     

Receiver operating characteristic analysis for environmental diagnosis. A potential application to endocrine disruptor screening: in vitro estrogenicity bioassays

The realization that certain chemicals are able to disrupt hormonal systems in humans and wildlife has challenged the way we assess risk from chemicals and led national and international agenciesto devise programsto screen chemicals for endocrine-disrupting properties. Chemicals capable of mimicking sex hormones, such as estrogens and androgens, have received the most attention, and although not yet validated, in vitro techniques to test for such properties are well developed. Receiver operating characteristic (ROC) analysis has been successfully used in the biomedical and military fields for several decades to assess the accuracy of diagnostic tests in terms of both their sensitivity and specificity. This approach is applied here to demonstrate its potential to assess how well in vitro bioassays can predict estrogenicity in vivo. Despite the limited availability of suitable data, the ROC curves obtained indicate that these bioassays are effective diagnostic tests. The potential sources of false positives and false negatives are identified and potential applications to endocrine disruptor screening programs discussed.     

Changes in surface configuration of the skin caused by ageing and application of cosmetics: three-dimensional analysis according to a new system based on image analysis and Fourier transformation

The surface configuration of the skin, as characterized by surface furrows and plateaux, is known to change with ageing and skin condition. There have been many attempts to analyse the surface configuration in order to evaluate the effect of skin care products. However, the systems proposed up to now are insufficient to obtain three-dimensional data.
A system based on image analysis and Fourier transformation has been developed. By using this system, we can make a quick and quantitative analysis of the three-dimensional surface configuration of the skin. This system was applied to measure changes in the surface configuration with ageing, and to clarify the effects of cosmetic cream.
As a result, it was found that the furrows become less clear, become parallel in one direction and the texture becomes coarse and irregular, as ageing continues. These changes are believed to correspond to deterioration of the metabolic and moisturizing functions of the skin.
It was also found that the furrows become clear and the texture becomes finer after the application of cream than before. This is believed to be the result of the improvement of the skin condition due to the moisturizing effect of the cream.     

The use of video image analysis for quantitative measurement of visible fat and lean in meat: Part 4- application of image analysis measurement techniques to minced meats

The quantitative measurement of fat in minced meat by video techniques has, to date, been impractical due to the nature of the raw material and camera limitations in particle resolution. The latter have been enhanced by improving the optical system and by illuminating the meat with a limited wavelength ultraviolet light source. Problems with fat smear and drip stain, causing over- and under-estimation of fat, respectively, have been overcome by better control of mincing conditions. Tempering of the meat to between -2°C and -5°C before mincing gave the best results. The level of fat detection was unchanged for up to 20 min after mincing, but, by 2 h, the initial value had fallen by 50%. Magnifying the field of view, thus reducing the sample size measured by 50%, did not adversely affect results with 4mm-10mm diameter mince. The system could not accurately resolve mince below 4 mm. Estimation of total lipid from video data using prediction equations was in good agreement with chemical analysis (r=0·99 for 10mm mince, r=0·95 for 4 mm mince). Video image analysis (VIA) can now be effectively extended to areas of meat processing using particulate meats.     

熟鱼silurus(Silurus glanis)的风味:通过感官分析和收集方法的比较来评价流体萃取物的风味特征

研究来自法国两个不同饲养环境的silurus(Silurus glanis)鱼的风味,对于熟鱼肉进行感官鉴评.通过流体萃取物的风味特征对其进行风味评价.比较了两种收集方法.两种养殖条件对熟鱼肉的风味有影响.在室外不进行换水饲养两年对比于在室内活水饲养一年发现鱼肉中干草味、青草味和热牛奶味较强,霉味、煮鸡蛋味和煮白菜味较弱.用铁氟龙容器收集风味物质提取物,比用玻璃长颈瓶收集风味描述更强,显示了流体萃取法与熟鱼风味分析的相关性.     

Odour of cooked silurus (Silurus glanis) flesh: evaluation by sensory analysis and comparison of collection methods to assess the odour representativeness of extracts obtained by dynamic headspace

The odour of silurus (Silurus glanis) coming from two types of rearing environment developed in France was studied. Odour sensory analysis was performed on cooked fillets of silurus. The odour representativeness of extracts obtained by dynamic headspace was assessed. Two methods of extract collection were compared. Rearing environment had an effect on the odour of cooked fillets of silurus. Silurus reared in outdoor ponds for 2 years with no renewal of water had a stronger odour of hay, cut grass and hot milk and a weaker odour of mouldy, hard‐boiled egg and cooked cabbage than silurus reared in indoor concrete ponds for 1 year with renewed geothermal water. Odour extracts collected with the Teflon bag method were more representative of the odour of cooked fillets of silurus than those collected with the glass flask method. Teflon bags showed the relevance of dynamic headspace extraction to analyse the odour of cooked fillets of silurus. Copyright © 2004 Society of Chemical Industry     

An innovative lab-scale strategy for the evaluation of Grape Processing Residues (GPR) filterability: Application to GPR valorization by ultrafiltration

The objective of this work was to characterize the foulant propensity of three Grape Processing Residues (GPR) in relation with their physicochemical properties. Therefore, a physicochemical characterization of GPR was firstly carried-out, with a focus on the separation/characterization of relevant size-classes of particles. Then, lab-scale experiments were performed using a dead-end filtration module with different membranes (three average pore diameters) in order to identify for each GPR the main foulant size-classes of particles and the related fouling mechanisms. Results showed that this study allowed getting more insight into how different fractions of GPR are involved in membrane fouling according to their size. Moreover, size-cartographies of GPR foulant compounds were built to provide a better understanding and control of membrane fouling. The obtained results showed that it was possible to use this simple and cost-effective tool to choose the appropriate filtration conditions.Industrial relevanceThe valorization of Grape Processing Residues (GPR) is a major economic and ecological challenge. GPR contain a high amount of phenolic compounds, well known for their several biological properties. In the light of this, membrane technologies have been widely used for the extraction and the purification of these bioactive compounds from GPR. However, the performance of these processes is highly challenged by membrane fouling, which is partially dependent on the feed suspension characteristics. To date, different operating strategies have been used industrially to prevent membrane fouling. However, the use of costly and time-consuming strategies has not often been validated by characterization of the feed suspension prior to filtration. Thus, it is mandatory to analyze GPR intrinsic characteristics in relation with their fouling in order to identify the appropriate operation conditions for large-scale filtration. For this purpose, an innovative strategy was developed in this work. This study was useful to develop a simple and cost-effective tool providing reliable guidelines for the development of efficient pilot-scale processes for the extraction of phenolic compounds from GPR.     

Development and application of a method for the analysis of two trichothecenes: deoxynivalenol and T-2 toxin in meat in China by HPLC-MS/MS

A reliable and sensitive method was developed and successfully applied for the determination of deoxynivalenol and T-2 toxin simultaneously in pig dorsal muscle, pig back fat and chicken muscle by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) analysis. Limit of detection of deoxynivalenol and T-2 was 0.02 μg/kg and 0.007 μg/kg, and limit of quantification of deoxynivalenol and T-2 was 0.07 μg/kg and 0.02 μg/kg, respectively. Sixty-six meat samples were analyzed and deoxynivalenol was detected in the samples of pig back fat, with concentrations lower than 0.5 μg/kg, and T-2 toxin was detected in the samples of pig dorsal muscle, pig back fat and chicken muscle, with concentrations lower than 0.5 μg/kg. The results of sample analysis show that only trace residues of deoxynivalenol and T-2 toxin were detected in the samples analyzed.